Mobile devices including smart phones, laptop computers, tablet computers, etc., can be powered by rechargeable battery packs that contain one or more rechargeable batteries such as lithium ion batteries. Lithium ion batteries provide several advantages and disadvantages over other types of rechargeable batteries. Lithium ion batteries tend to be lighter, provide higher energy densities, and have a slower loss of charge when not in use. On the other hand, if overcharged, lithium ion batteries may combust. Further, a deep discharge of lithium ion batteries below a voltage threshold (e.g., 2.4 volts-2.8 volts per cell, depending on the chemistry) may result in a dead battery.
The use of the same reference symbols in different drawings indicates similar or identical items.